Following Sebastian Kurz’s resignation as chancellor at the weekend, Austrian opposition parties agreed on Wednesday to form a parliamentary commission to investigate allegations of corruption by officials from the ruling conservative party.

Kurz denies guilt, but he has been arrested along with nine others, including senior staffers, on suspicion of corruption related to the use of public funds to sway public opinion in favor of Kurz when he ran for party leader and later chancellor.

To salvage his coalition, he stood down on Saturday at the request of his junior coalition partner, the Greens. He was succeeded as chancellor by close supporter Alexander Schallenberg, a diplomat and political newbie who says he will work closely with Kurz, the party’s leader.

“We believe that what we’ve seen so far is simply the top of the iceberg,” Social Democrat politician Kai Jan Krainer told a joint news conference with colleagues from the other two opposition parties in parliament.

In Austria, parliamentary inquiry commissions have the authority to confiscate papers and interview witnesses under oath.

An earlier commission on possible corruption under Kurz’s previous coalition with the far right obtained troves of text-message exchanges that became part of prosecutors’ corruption case against Kurz and others.

Kurz is separately under investigation on suspicion of perjury over testimony he gave to that commission. Kurz, who is now also taking over as his party’s top lawmaker in parliament, says all allegations against him are false.

While the opposition parties can set up such a commission without the two ruling parties’ support, Krainer said Kurz’s conservatives can delay its approval and it might not be able to hold its first session until next year.